The studies proposed concern the synthesis of new membrane proteins after T5-bacteriophage infection of Escherichia coli and the role of these proteins in DNA transport through the membrane, host DNA breakdown, the control of protein synthesis, and the maintenance of energy producing systems. Experiments on membrane protein synthesis and membrane function will be conducted in both a system in which T5 can replicate normally and in the presence of the colicin Ib factor, a plasmid which causes infection of T5 to be abortive. The abortive infection results from the interaction of a plasmid protein and a phage protein and we believe this to cause aberrant membrane function. Included in the experiments will be a purification of the T5-induced Al protein solubilized from the membranes of infected cells, a study of the association of this protein with and its effect upon cell membrane components and phage and host DNA, a determination of the genes controlling the synthesis of three other T5-induced membrane proteins, a study of membrane function during the abortive infection of T5 in the presence of the colocin Ib factor, and experiments to determine the mechanism and genes involved in the inactivation of the cell surface receptors for T5 after infection.